Many different industrial waste materials are managed by being placed into landfills or reservoirs. These varying waste materials are often considered to be a possible source of groundwater contamination. In an effort to protect human health and the environment, Federal and/or state environmental regulations require “closure” of such waste sites. Traditional closure is generally garnered by either leaving the waste in place and installing a “Cover System” or through the removal and decontamination of the waste site.
Cover Systems may differ from waste to waste and site to site, depending on state-specific requirements and site specific conditions. However, Cover Systems are normally comprised of layers of both manufactured materials and natural materials.
For example, according to the Ohio EPA Requirements, impoundment closure system for coal combustion residuals (CCRs) should include a minimum post-settlement slope of (1) percent, one (1) foot of suitable fertile soil cover for the top layer, and two (2) feet of clay/cohesive soil with a permeability of 1×10−6 centimeters per second (cm/s) or less on top of the CCR.
Traditional closure systems requires heavy earthwork, in the form of material fill placement and/or waste stabilization, waste excavation and, movement, to achieve the minimum surface slopes required for installation of the Cover System. Earthwork on top of many waste material is often problematic due to the inadequate bearing capacity, potential for localized liquefaction, differential settlement, and inadequate slope stability. In some cases fatalities have occurred due to unstable conditions encountered during earthwork on the surface of waste disposal sites. In addition, the schedule and costs required to install a traditional Cover System in these conditions are excessive in comparison to construction over more stable materials.
This invention provides alternative, superior methods and materials for landfill or impoundment closure systems on waste disposal sites that can be utilized at less cost and with greater safety than traditional systems. Finally, the invention impounds shallow water on the Cover System (see FIG. 1), to provide superior and more diverse habitat in comparison to traditional closure systems (i.e., FIG. 2).